The present invention is directed to a novel process for the ammoxidation of a mixture of alcohols to a mixture of nitriles. In particular, the present invention is directed to increasing the yield and, preferably, the ratio of co-product hydrogen cyanide and acetonitrile produced during the ammoxidation of propylene to acrylonitrile.
There are several patents which address the issue of the injection of methanol or ethanol into a fluid bed reactor to produce hydrogen cyanide or acetonitrile. In addition, these references further disclose that the methanol or ethyl alcohol may be introduced into a fluid bed reactor to increase the co-product hydrogen cyanide or acetonitrile while manufacturing acrylonitrile. For example, U.S. Pat. Nos. 3,911,089; 4,485,079 and 5,288,473 are directed to the ammoxidation of methanol to produce hydrogen cyanide by injection of the methanol into the fluid bed reactor containing the ammoxidation catalyst suitable for the manufacture of acrylonitrile. Each of these references teach that methanol injection can be made simultaneously with the manufacture of acrylonitrile. In addition, Japanese Patent Applications 74-87,474; 79-08,655; and 78-35,232 relate to similar methods of increasing the yield of hydrogen cyanide during the manufacture of acrylonitrile. Japanese Patent Application 2[1990]-38,333 is directed to improving acetonitrile yields by injecting acetone and/or ethyl alcohol into an ammoxidation reactor containing ab ammoxidation catalyst. The process disclosed in the Japanese Patent Application includes simultaneously injecting the acetone and/or ethyl alcohol into the ammoxidation reactor while manufacturing acrylonitrile. All of these patents are concerned with the production of either additional hydrogen cyanide or acetonitrile.
The present invention is directed to a process which increases the yield of one or both main co-products (i.e. HCN and acetonitrile) during the manufacture of acrylonitrile while (1) saving on the raw material costs associated with the increase in co-product yields and (2) achieving the same or better conversion and selectivity to the desired co-products (on a carbon basis) as one obtains with the use of neat alcohols such as methanol/ethanol. The relative amounts of hydrogen cyanide and acetonitrile can be controlled by the process of this invention.
We have found, unexpectedly, that the use of crude alcohol mixtures can attain a desirable increase in the production of acetonitrile and hydrogen cyanide during the production of acrylonitrile.